1. Field of the Invention
The present invention relates to an antenna diversity receiver applicable to an orthogonal frequency division multiplexing (OFDM) system, and more particularly, to an antenna diversity receiver that can reduce power consumption by detecting the power of a receive (RX) signal at a front end of an analog-to-digital (A/D) converter, i.e., a radio frequency (RF) module unit, and can further reduce the power consumption by determining a wake-up mode at the RF module unit according to the power of an RX signal.
2. Description of the Related Art
Generally, in a radio frequency (RF) receiver, the strength of a receive (RX) signal varies with time due to indoor multipath fading. In order to improve an RX sensitivity by removing the time-dependent multipath fading, the RF receiver uses a frequency diversity scheme and a space diversity scheme.
An example of an antenna diversity receiver using an antenna diversity scheme corresponding to the space diversity scheme will be described with reference to FIG. 1.
FIG. 1 is a block diagram of a related art antenna diversity receiver.
Referring to FIG. 1, the related art antenna diversity receiver includes first and second antennas ANT1 and ANT2, an antennal selector unit 10, an RF module unit 20, an A/D converter 30, a power detector 50, and a selection controller unit 60. The antenna selector unit 10 selects one of the first and second antennas ANT1 and ANT2. The RF module unit 20 converts an RF RX signal received from the antenna selector unit 10 into a baseband RX signal. The A/D converter 30 converts the RX signal received from the RF module unit 20 into a digital signal. Using the digital signal received from the A/D converter 30, the power detector 50 detects the power of an RX signal received through each of the first and second antennas ANT1 and ANT2. According to the power level detected by the power detector 50, the selection controller unit 60 selects the antenna with a relatively high RX power.
The RF module unit 20 includes a low-noise amplifier (LNA) 21, a mixer 22, a band-pass filter (BPF) 23, and a variable-gain amplifier (VGA) 24. The low-noise amplifier 21 low-noise amplifies the RF RX signal received from the antenna selector unit 10. The mixer 22 converts the RF RX signal received from the low-noise amplifier 21 into a baseband RX signal. The band-pass filter 23 passes an RX signal of a predetermined band among the RX signals received from the mixer 22. The variable-gain amplifier 24 amplifies the signal received from the band-pass filter 23.
In this way, the related art antenna diversity receiver uses the A/D converter 30 to analyze and compare the strengths of the signals received from the RF module unit 20, thereby selecting the antenna with a high RX signal strength.
However, in the related art antenna diversity receiver illustrated in FIG. 1, the low-noise mixer 21, mixer 22, band-pass filter 23, and variable-gain amplifier 24 of the RF module unit 20 and the A/D converter 30 must be all operated in order to select the antenna with a good RX sensitivity among the first and second antennas ANT1 and ANT2, thus causing large power consumption.